• Proceedings of the KIEE Conference
• /
• 2007.10c
• /
• pp.56-58
• /
• 2007

AC transport current losses is an important factor in the development of superconducting tapes and superconducting power applications. In this paper we compared measurement, calculation and Norris equation of AC transport current loss in BSCCO single and multi stacked wire. And present a distribution flux density and current density in the HTS single wire and multi stacked wire. The result of Measurement and calculation of Ac transport current loss show that the same. And show that HTS characteristic of inside HTS wire.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.39 no.2
• /
• pp.39-45
• /
• 2002

A new EMI estimation technique concerned with a PDP system is presented. A physical circuit model is developed which can fairly well describe the AC-PDP system. EMIs of the PDP system are quantitatively determined by combining circuit model and Hertzian dipole antenna model. The simulation results are experimentally verified with the test panel. The AC PDP system was measured in the frequency range of 30MHz~300MHz in a semi-anechoic chamber, according to CISPR 13 code. Thereby, it is shown that the proposed technique can be usefully employed for EMI reduction.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.8 no.2
• /
• pp.351-358
• /
• 2018

Reinforcement learning is a machine learning method which aims to determine a policy to get optimal actions in dynamic and stochastic environments. But reinforcement learning has high computational complexity and needs a lot of time to get solution, so it is not easily applicable to uncertain and continuous environments. To tackle the complexity problem, AC (actor-critic) method is used and it separates an action-value function into a value function and an action decision policy. Also, in transfer learning method, the knowledge constructed in one environment is adapted to another environment, so it reduces the time to learn in a reinforcement learning method. In this paper, we present AC method and transfer learning method to solve the problem of a reinforcement learning method. Finally, we analyze the case study which a transfer learning method is used to solve BS(base station) switching problem in wireless access networks.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.5 s.96
• /
• pp.455-464
• /
• 2005

We have proposed a model of a thermal voltage converter(TVC) using the trans-impedance of lossy transmission line and developed a calculation program for ac-dc transfer difference of the TVC. The proposed TVC consists of a thermo-element(f) and a range resistor wire connected in series at the center of coaxial cylinder. The range resistor wire is used to extend the measurement range of the n. The calculated ac-dc transfer differences of the proposed TVC by simulation agree well with the measured values within the uncertainties. The simulated and measured values are agreed within $1{\mu}V/V$ from 40 Hz to 10kHz, within $5{\mu}V/V$ from 20kHz to 100MHz, and within $12{\mu}V/V$ from 200kHz to 1 MHz.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.11a
• /
• pp.743-746
• /
• 2005

본 논문에서는 디지털 비디오 인코딩 과정의 VLC(variable length coding) 영역에서 블록계층의 DC/AC 성분을 이용한 인증과 서명의 이중 비디오 워터마킹 시스템을 제안하였다. 제안한 기법은 블록계층의 DC 성분과 AC 성분에서 HVS(human visual system)의 특성을 고려한 것이다. 인증 워터마킹은 주요한 정보를 포함하는 저주파 영역과 윤곽선 정보를 포함하는 중간 주파수 영역을 이용하여 인트라 프레임의 DC 성분과 움직임 벡터의 부호를 변형시켰고, 서명 워터마킹은 모든 프레임의 AC 성분들 중에서 마지막 AC 성분의 Level이 '1'인 경우에만 워터마크를 삽입하였다. 서명 워터 마크 검출은 저작권자의 비밀 키에 의해서만 가능하고, 기술적인 면에서 저자권자의 판별 기준이 될 수 있다. 제안한 이중 비디오 워터마킹 시스템의 특징은 인증과 서명의 두 가지 기능을 선택적으로 수행할 수 있으며, 계산과정이 복잡하지 않으면서 비트 스트림(bit-stream)을 유지시킨다. 그리고 실험 결과에서 기존의 방법보다 화질 면에서 $2{\sim}3dB$ 더 높은 수치를 얻어 우수함을 보였고, 인코딩 수행 속도에 미치는 영향은 거의 없었으며, 향후 실시간 인코딩 처리에 응용될 수 있다.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.973_974
• /
• 2009

본 연구는 영구자석 AC 동기전동기의 초기 기동제어에 대하여 연구하였다. 회전자 위치 검출용 센서는 홀센서를 사용하였고 전동기 운전을 벡터제어를 사용하기 위해 전동기가 정지된 상태에서 홀센서 신호에 따른 회전자 위치를 계산하였다. 견인전동기가 주행저항 보다 큰 견인력을 내기 위해 전동기를 BLDC로 기동한 후 안정적 운전을 위해서 벡터제어로 전환하였다.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1037-1039
• /
• 2002

가전산업과 연계하여 유도가열 기술을 응용한 대표적인 시스템으로 IH압력밥솥을 예로 들 수 있다. 유도가열 코일에서 고주파 자속의 의해 발생된 와전류가 결합된 밥솥을 가열하기 때문에 유도가열 코일에는 고주파 손실을 줄이기 위해 Litz wire가 사용된다 이에 본 논문은 특히 IH압력밥솥에 사용되는 Litz wire를 선정하는 데 있어 중요한 요소가 되는 소선경, 가닥수별 AC DC 저항 및 손실계산 그리고 Cost 예측 방법을 제안한다.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.3
• /
• pp.345-351
• /
• 2014

Purpose: The accommodative response and the near horizontal phoria were examined with additional spherical power to analyze the stimulus and response AC/A ratios that suggest reference data for the binocular vision. Methods: The open-field autorefractometer (Nvision-K 5001, Shin nippon) and modified thorington method (MIM card; Muscle Imbalance Measure card, Bernell) at 40 cm were utilized to measure the accommodative response and the near horizontal phoria for 81 persons ($20.89{\pm}1.92$ years old) with additional spherical power. The stimulus and the response AC/A ratios were calculated by gradient AC/A method. Results: The exophoria group showed the highest accommodative response ($1.92{\pm}0.26D$) at 40 cm, followed by orthophoria group and esophoria group($1.72{\pm}0.26D$ and $1.62{\pm}0.42D$, respectively) Meanwhile, the esophoria group showed the biggest ocular deviation for the near ($23.24{\Delta}$) followed by the orthophoria group and exophoria group ($19.76{\Delta}$ and $15.14{\Delta}$, respectively). The biggest difference of the stimulus and the response AC/A ratios was $1.72{\Delta}$ for the exophoria group with -2.00 D, while the one was $3.43{\Delta}$ for the esophoria group with +1.00 D. There was a significant difference between AC/A ratios for the exophoria group with -2.00 D, -1.00 D and the esophoria group with +3.00 D, +2.00D, +1.00D and -1.00D. Conclusions: The difference between stimulus and response AC/A was greater when increased minus spherical power for the exophoria group, while it was greater when increased plus spherical power for the esophoria group. Furthermore, the difference for the esophoria group was a greater than the one for the exophoria group.

• Journal of KIISE:Computing Practices and Letters
• /
• v.14 no.2
• /
• pp.191-195
• /
• 2008

This paper proposes a technique for improving IEEE 802.11e EDCA's performance by dynamically adjusting each class's contention window size based on each class's traffic amount. For providing differentiated service differently from 802.11, 802.11e EDCA maintains four classes each of which specifies different static minimum and maximum contention window sizes. Since the initial window sites significantly affect the 802.11e performance, several window adjustment schemes have been proposed. One of the schemes known as CWminAS (CWmin Adaptation Scheme) dynamically and synchronously determines the four windows' site based on the periodically measured collision rate. This method, however, can lower the send probability of high priority classes since it can't differentiate their collisions from those of low priority classes, leading to the channel underutilization. For solving this problem, we propose ACATICT(Adaptive Contention-window Adjustment Technique based on Individual Class Traffic) algorithm which adapts each class window size based on each individual collision rate rather than one average collision rate. Our simulation experiments show that ACATICT achieves better utilization by around 10% at maximum.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1074-1077
• /
• 2003

우리는 AC-PDP에서 휘도와 효율을 향상시키기 위하여 Ne-Xe(4%)와 He(7)-Ne(3)-Xe(3%)에 소량의 Ar 또는 Kr를 첨가하여 최적의 페닝 방전가스 혼합비를 연구하였다. 우리는 이것을 증명하기 위해 효율과 Q-V 방법을 이용하여 벽전하를 계산하였으며, 2차원 시뮬레이션에서의 결과값과 비교하였다. 200 Torr 압력에서 He-Ne-Xe 또는 Ne-Xe에 소량의 Ar(0.01-0.1%) 또는 Kr(0.01-0.1%)을 첨가시켰을 때, 우리는 20% 이상의 휘도의 증가와 25% 이상의 효율 증가를 발견하였고, 또한 벽전하도 25% 이상의 증가를 보였다. 400 Torr 압력에서 He-Ne-Xe-Kr(0.005%)에 소량의 Ar(0.005-0.1%)를 첨가시켰을 때는 8% 이상의 휘도의 증가와 18% 이상의 효율 증가, 12% 이상의 벽전하 증가를 확인하였다. 결론적으로 이 결과는 He, Ne, Ar, Kr 사이에 추가적인 페닝효과가 휘도와 효율을 향상시켰다는 것을 보여준다.